The usual citrus concentrated aromas which are commercially available are fruit juice products which have an alcohol content of 8 to 15% by weight and are concentrated more than 500 times by using essence recovery units attached to a T.A.S.T.E. (Thermally Accelerated Short Time Evaporator). Also, highly concentrated products of the concentrated aroma are commercially available. In the production of these concentrated aromas, the loss of low boiling point fractions is prevented, for example, by improving the refining ability of a distilling column and by flowing liquid ammonia through a condenser. However, not only can these fractions not be collected, but also it takes a long time for the concentrating operation to increase the degree of concentration (see J. Agric. Food Chem. 1990, 38, 2181).
With regard to the flavor of fruit juice, it is known that the flavorous component is obtained by extraction using an organic solvent which can be separated from water. However, this method has not been used very often on account of its high cost. While, for the purpose of collecting low boiling point fractions efficiently and preventing a change of flavor caused by heating, the separation of flavorous substances by using a spinning cone column (hereinafter simply referred to as "SCC") and mass-transfer equipment. Such methods are explained in "1st Conference of Food Engineering, 1991, AlchE, Chicago, Ill.," herein incorporated by reference. Also, it is disclosed in the specification of WO 90/02493 that vegetables and fruits such as tomatoes, apples and pears are processed using the SCC to obtain a high viscosity component having a low flavor.
There are detailed descriptions concerning the design of a column of the SCC in "I.
Chem. E. Symp. Series, A128, 167-179, 1992. The SCC is also used in a process of the recovery of volatile components such as flavors wherein a volatile component (ethanol) is recovered at lower temperatures from a culture solution of fermented yeast (see Process Biochemistry, Vol. 31, No. 7, pp. 651-658, 1995).
A method for removing flavorous components from fruit juice is disclosed in the publication of JP-B-7-22646. In this method using equipment which removes aromas from fruit juice by utilizing the SCC used also in the present invention, the operation of removing these aromas is carried out in the column and the fruit juice whose aroma is removed is refined and subjected to filtration and thereafter the fruit juice is concentrated without the deterioration of flavorous components. The fruit juice is directly introduced into the SCC and treated in the following condition in the case of oranges: flow rate: 5,000 L/hr, operating temperature: 65.degree. C., operating pressure: 60 kPa, flow rate of recovery flavor: 75 L/hr and ratio to total fruit juice: 1:50.
There is a report that in the recovery of the flavorous components of apples and red berry fruits, the level of the content of free and combined sulfurous acid is lowered to 5 ppm or less (Food and Container, Vol. 39, No. 7, pp. 406-408, 1988). In the recovery of flavorous components in Flavourtech (see the specification of U.S. Pat. No. 4,996,945), high recovery rates are obtained in the processing of beers, apples, oranges, grapes, apricots or strawberries.